Solid state imaging device

Abstract

A CCD image sensor includes photodiodes, vertical transfer CCDs for transferal of signal charge of the photodiodes, and a light shielding layer for protection of the vertical transfer CCDs from light. The light shielding layer covers over recesses disposed above the photodiodes, and each of the recesses has an opening on the bottom to expose a light receiving surface of the photodiode. A light diffusion layer is formed on the light shielding layer in each recess. Since the incident light oblique to an optical axis of a microlens is diffused by the light diffusion layer, the vertical CCDs hardly receive the light coming from around the edges of the opening.

1. A solid state imaging device having a plurality of photodiodes for photoelectric conversion, comprising:
 a plurality of recesses each formed above one of said photodiodes; 
 a light shielding layer covering over said recesses while uncovering an opening at a bottom of each of said recesses; and 
 a light diffusion layer or light absorbing layer formed on said light shielding layer in each of said recesses while uncovering an opening at a bottom of each of said recesses, wherein said light diffusion layer and said light absorbing layer are made of a base material and inorganic fine particles or organic fine particles mixed thereto, and further wherein said inorganic fine particle for said light diffusion layer is Al 2 O 2  or TiO 2 . 
 
     
     
       2. A solid state imaging device described in  claim 1 , further comprising:
 transfer electrodes disposed beside said photodiodes and used for transferal of signal charge stored in said photodiodes, said transfer electrodes being formed on a semiconductor substrate having said photodiodes; and 
 an insulating layer covering both said transfer electrodes and said photodiodes while defining said recesses, said light shielding layer being formed on said insulating layer. 
 
     
     
       3. A solid state imaging device described in  claim 1 , further comprising:
 optical lenses provided for each of said photodiodes, 
 wherein said light diffusion layer or said light absorbing layer is disposed outside an optical path of incident light substantially parallel to an optical axis of said optical lens. 
 
     
     
       4. A solid state imaging device described in  claim 1 , wherein said base material is BPSG (boro-phospho silicate glass). 
     
     
       5. A solid state imaging device described in  claim 1 , wherein said base material is P-TEOS (plasma tetra ethyl ortho silicate). 
     
     
       6. A solid state imaging device having a plurality of photodiodes for photoelectric conversion, comprising:
 a plurality of recesses each formed above one of said photodiodes; 
 a light shielding layer covering over said recesses while uncovering an opening at a bottom of each of said recesses; and 
 a light diffusion layer or light absorbing layer formed on said light shielding layer in each of said recesses while uncovering an opening at a bottom of each of said recesses, wherein said light diffusion layer and said light absorbing layer are made of a base material and inorganic fine particles or organic fine particles mixed thereto, and further wherein said organic fine particle for said light diffusion layer is a polymer fine particle with plural holes on its surface. 
 
     
     
       7. A solid state imaging device having a plurality of photodiodes for photoelectric conversion, comprising:
 a plurality of recesses each formed above one of said photodiodes; 
 a light shielding layer covering over said recesses while uncovering an opening at a bottom of each of said recesses; and 
 a light diffusion layer or light absorbing layer formed on said light shielding layer in each of said recesses while uncovering an opening at a bottom of each of said recesses, wherein said light diffusion layer and said light absorbing layer are made of a base material and inorganic fine particles or organic fine particles mixed thereto, and further wherein said inorganic fine particle for said light absorbing layer is ferric oxide or a barium sulfate with iron oxide coating. 
 
     
     
       8. A solid state imaging device having a plurality of photodiodes for photoelectric conversion, comprising:
 a plurality of recesses each formed above one of said photodiodes; 
 a light shielding layer covering over said recesses while uncovering an opening at a bottom of each of said recesses; and 
 a light diffusion layer or light absorbing layer formed on said light shielding layer in each of said recesses while uncovering an opening at a bottom of each of said recesses, wherein said light diffusion layer and said light absorbing layer are made of a base material and inorganic fine particles or organic fine particles mixed thereto, and further wherein said organic fine particle for said light absorbing layer is a carbon fine particle or nano-carbon fine particle.